[GFS2] Fix unlinked file handling

This patch fixes the way we have been dealing with unlinked,
but still open files. It removes all limits (other than memory
for inodes, as per every other filesystem) on numbers of these
which we can support on GFS2. It also means that (like other
fs) its the responsibility of the last process to close the file
to deallocate the storage, rather than the person who did the
unlinking. Note that with GFS2, those two events might take place
on different nodes.

Also there are a number of other changes:

 o We use the Linux inode subsystem as it was intended to be
used, wrt allocating GFS2 inodes
 o The Linux inode cache is now the point which we use for
local enforcement of only holding one copy of the inode in
core at once (previous to this we used the glock layer).
 o We no longer use the unlinked "special" file. We just ignore it
completely. This makes unlinking more efficient.
 o We now use the 4th block allocation state. The previously unused
state is used to track unlinked but still open inodes.
 o gfs2_inoded is no longer needed
 o Several fields are now no longer needed (and removed) from the in
core struct gfs2_inode
 o Several fields are no longer needed (and removed) from the in core
superblock

There are a number of future possible optimisations and clean ups
which have been made possible by this patch.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/gfs2/ops_vm.c b/fs/gfs2/ops_vm.c
index 263c1fb..08709f1 100644
--- a/fs/gfs2/ops_vm.c
+++ b/fs/gfs2/ops_vm.c
@@ -38,15 +38,15 @@ static void pfault_be_greedy(struct gfs2_inode *ip)
 	ip->i_last_pfault = jiffies;
 	spin_unlock(&ip->i_spin);
 
-	gfs2_inode_hold(ip);
+	igrab(&ip->i_inode);
 	if (gfs2_glock_be_greedy(ip->i_gl, time))
-		gfs2_inode_put(ip);
+		iput(&ip->i_inode);
 }
 
 static struct page *gfs2_private_nopage(struct vm_area_struct *area,
 					unsigned long address, int *type)
 {
-	struct gfs2_inode *ip = area->vm_file->f_mapping->host->u.generic_ip;
+	struct gfs2_inode *ip = GFS2_I(area->vm_file->f_mapping->host);
 	struct gfs2_holder i_gh;
 	struct page *result;
 	int error;
@@ -69,7 +69,7 @@ static struct page *gfs2_private_nopage(struct vm_area_struct *area,
 
 static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
 {
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	unsigned long index = page->index;
 	uint64_t lblock = index << (PAGE_CACHE_SHIFT -
 				    sdp->sd_sb.sb_bsize_shift);
@@ -114,7 +114,7 @@ static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
 		unsigned int extlen;
 		int new = 1;
 
-		error = gfs2_extent_map(ip->i_vnode, lblock, &new, &dblock, &extlen);
+		error = gfs2_extent_map(&ip->i_inode, lblock, &new, &dblock, &extlen);
 		if (error)
 			goto out_trans;
 
@@ -142,7 +142,7 @@ static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
 static struct page *gfs2_sharewrite_nopage(struct vm_area_struct *area,
 					   unsigned long address, int *type)
 {
-	struct gfs2_inode *ip = area->vm_file->f_mapping->host->u.generic_ip;
+	struct gfs2_inode *ip = GFS2_I(area->vm_file->f_mapping->host);
 	struct gfs2_holder i_gh;
 	struct page *result = NULL;
 	unsigned long index = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) +